[jboss-jira] [JBoss JIRA] Commented: (JGRP-1066) Introduce dependencies for @Property annotations

[Richard Achmatowicz (JIRA)]

    [ https://jira.jboss.org/jira/browse/JGRP-1066?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12487926#action_12487926 ] 

Richard Achmatowicz commented on JGRP-1066:
-------------------------------------------

The modifications are in:
- Property.java (change to convert method signature)
- PropertyConverters.java (adding new PropertyConverter for InitialHosts)
- Configurator (adding in depenency processing method computePropertyDependencies which takes a Protocol and creates and ordered list of @Property annotated Field and Methods, ordered in such a way as to be consistent with depenencies specified. The ProrocolConfiguration.createLayer() went from this:

removeDeprecatedProperties(retval, properties);
resolveAndAssignFields(retval, properties) ;
resolveAndInvokeMethods(retval, properties)

to this:

removeDeprecatedProperties(retval, properties);  // before processing Field and Method based properties, take dependencies specified with @Property.dependsUpon into account
AccessibleObject[] dependencyOrderedFieldsAndMethods = computePropertyDependencies(retval) ;
for(AccessibleObject ordered: dependencyOrderedFieldsAndMethods) {
 if (ordered instanceof Field) {
    resolveAndAssignField(retval, (Field)ordered, properties) ;
 }
 else if (ordered instanceof Method) {
    resolveAndInvokePropertyMethod(retval, (Method)ordered, properties) ;                        }
}

I've left the processing of ConfigurableObjects without depenency processing, but the same lines of code can be used to implement it there too.


> Introduce dependencies for @Property annotations
> ------------------------------------------------
>
>                 Key: JGRP-1066
>                 URL: https://jira.jboss.org/jira/browse/JGRP-1066
>             Project: JGroups
>          Issue Type: Feature Request
>    Affects Versions: 2.8
>            Reporter: Richard Achmatowicz
>            Assignee: Richard Achmatowicz
>            Priority: Minor
>             Fix For: 2.8
>
>
> When processing properties annotated by @Property in protocols, there is a need to reference one property when processing anoither; an example is that the setting of initial_hosts requires a list of host[port] entries, as well as a port_range value. Usually, this sort of property processing requirement forced delaying the processing of initial_hosts in the init() phase, after protocol property processing had completed. 
> We introduce a dependency mechanism for @Property annotations:
> 1. @Properties have a name - it can either be explicitly specified in the annotation
> @Property(name=X)
> int i = 0 ;
> or it can default to the variable name of a Field
> @Property(desc=...)
> int Y = 0 ;
> ir it can default to the method name without the prefix set.
> @Property(desc=...)
> void setZ(int i)
> 2. You can specify a dependency on one or more properties (fields or methods) in the same protocol by specifying a comma separated list of @Property names in a dependsUpon attribte:
> @Property(name="X", desc=..., dependsUpon="Y,Z")
> int i = 0 ;
> This ensures that properties Y and Z will be processed by their converters (default or specified) before property X is processed.
> 3. Which leads to the main reason for introducing dependscies: in this way, the converter for property X may refer to the converters for property Y and Z in its processing.
>    public static class InitialHosts implements PropertyConverter{
>        public Object convert(Protocol protocol, Class<?> propertyFieldType, Properties props, String propertyValue) throws Exception {
>            int port_range = getPortRange(protocol) ;
>            List<IpAddress> addresses = Util.parseCommaDelimitedHosts(propertyValue, port_range) ;               return addresses ;
>        }
>        private int getPortRange(Protocol protocol) {
>            int port_range = 0 ;              try {
>                Field f = protocol.getClass().getDeclaredField("port_range") ;
>                port_range = ((Integer) Configurator.getField(f,protocol)).intValue() ;
>            }
>            catch(NoSuchFieldException e) {                  System.out.println("InitialHosts: no such field: port_range");
>            }
>            return port_range ;
>        }
>    }

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